The invention relates to a hydrostatic machine according to the precharacterising clause of claim 1.
A hydrostatic machine of this type is described in DE 195 12 993 A1.
This known hydrostatic machine is a so-called double-pump unit with a one-piece main housing body having a centrally arranged housing centre wall and on each side a housing end wall, respective housing chambers being arranged between the housing centre wall and the housing end walls, in which housing chambers respective cylinder drums with pistons guided therein such that they can be displaced substantially axially to and fro are arranged, which pistons are supported on a swivelling body likewise arranged in the housing chamber. The cylinder drums are mounted on respective drive shafts which internally are rotatably mounted in bearing bores of the housing centre wall and externally pass through the associated housing end wall in a bearing hole and are likewise rotatably mounted therein. Each swivelling body is assigned an adjusting device with an adjusting element movable to and fro and likewise mounted, such that it can be displaced to and fro, in the one-piece main housing body. The two drive shafts of the first and second hydrostatic unit thus formed are connected to each other in a rotationally fixed manner in the region of the housing centre wall by a coupling piece in the form of a muff. In this known hydrostatic machine, the housing chambers are assigned a respective access opening which is arranged transversely to the associated drive shaft and through which the associated swivelling body is mountable and demountable. The access openings are closable by a respective covering plate, on which bearing surfaces for a swivelling bearing of the associated swivelling body are formed. On the side opposite the covering plates, bearing surfaces for the swivelling bodies are arranged on the one-piece main housing body. Whereas one housing end wall serves as a mounting-on flange for the hydrostatic machine, onto the other housing end wall is mounted an auxiliary pump which is driven by the associated drive shaft projecting into the auxiliary pump body.
This known design is disadvantageous for several reasons. First of all, the main housing body is not only of a complicated structural shape due to the additional presence of the transversely directed access openings, but is also considerably weakened by the access openings, so that the main housing body must be stably designed in its remaining structural sections to be able to take the stresses placed upon it in operation. A further disadvantage is that two additional covering plates have to be provided, as a result of which not only is the number of components increased, but they have also to be mounted and sealed and they contribute to the complicated construction. Moreover, in this known design, the swivelling bearings for the swivelling bodies are each formed partly on the main housing body and partly on the associated covering plate. A further disadvantage with this is that, owing to scarcely avoidable tolerances, positional differences between the bearing surfaces arranged on the main housing body and the bearing surfaces arranged on the covering plates are to be expected, which leads to impairment of the swivelling bearings for the swivelling bodies, in particular under high stresses, as a result of which the service life of the swivelling bearings and thus also of the hydrostatic machine as a whole can be impaired.